Liquid crystal display device

ABSTRACT

A liquid crystal display device includes a first glass substrate, a second glass substrate, a first liquid crystal layer disposed between the first glass substrate and the second glass substrate, a third glass substrate, a fourth glass substrate, a second liquid crystal layer disposed between the third glass substrate and the fourth glass substrate, a first polarizing plate formed on the first glass substrate, a second polarizing plate formed on the third glass substrate, and a bonding layer disposed between the first glass substrate and the third glass substrate. In planar view, the bonding layer is disposed outside the first polarizing plate and the second polarizing plate, a surface on the bonding layer bonds to the first glass substrate, and a surface on the bonding layer bonds to the third glass substrate.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese application JP2017-068347 filed on Mar. 30, 2017, the content of which is herebyincorporated by reference into this application.

TECHNICAL FIELD

The present invention relates to a liquid crystal display device.

BACKGROUND

A technique, in which two display panels overlap each other and an imageis displayed on each display panel based on an input video signal, hasbeen conventionally proposed to improve contrast of a liquid crystaldisplay device (for example, see Unexamined Japanese Patent PublicationNo. 2010-66353). Specifically, for example, a color image is displayedon a front-side (observer-side) display panel in two display panelsdisposed back and forth, and a black-and-white image is displayed on arear-side (backlight-side) display panel, thereby improving contrast.

In the conventional liquid crystal display device, the two displaypanels are stuck and fixed using a bonding agent, such as a UV curableresin, which is applied onto whole surfaces opposite to each other inthe two display panels. However, in the configuration of theconventional liquid crystal display device, it is necessary to apply thebonding agent onto the whole surfaces of the two display panels, whichresults in a cost increase.

An object of the present disclosure is to reduce the cost of the liquidcrystal display device in which the plurality of display panels overlapeach other.

SUMMARY

According to one aspect of the present disclosure, a liquid crystaldisplay device in which a plurality of display panels are disposed whileoverlapping each other, and an image being displayed on each of thedisplay panels, the liquid crystal display device includes: a firstglass substrate; a second glass substrate disposed opposite to a firstdirection with respect to the first glass substrate; a first liquidcrystal layer disposed between the first glass substrate and the secondglass substrate; a third glass substrate disposed opposite to the firstglass substrate in a second direction, the second direction being anopposite direction to the first direction with respect to the firstglass substrate; a fourth glass substrate disposed opposite to thesecond direction with respect to the third glass substrate; a secondliquid crystal layer disposed between the third glass substrate and thefourth glass substrate; a first polarizing plate formed in a firstsurface on a second direction side of the first glass substrate; asecond polarizing plate formed in a first surface on a first directionside of the third glass substrate; and an bonding layer disposed betweenthe first glass substrate and the third glass substrate. In planar view,the bonding layer is disposed outside the first polarizing plate and thesecond polarizing plate, a surface on the first direction side of thebonding layer bonds to the first surface of the first glass substrate,and a surface on the second direction side of the bonding layer bonds tothe first surface of the third glass substrate.

According to another aspect of the present disclosure, a liquid crystaldisplay device in which a plurality of display panels are disposed whileoverlapping each other, and an image being displayed on each of thedisplay panels, the liquid crystal display device includes: a firstglass substrate; a second glass substrate disposed opposite to a firstdirection with respect to the first glass substrate; a first liquidcrystal layer disposed between the first glass substrate and the secondglass substrate; a third glass substrate disposed opposite to the firstglass substrate in a second direction, the second direction being anopposite direction to the first direction with respect to the firstglass substrate; a fourth glass substrate disposed opposite to thesecond direction with respect to the third glass substrate; a secondliquid crystal layer disposed between the third glass substrate and thefourth glass substrate; a first polarizing plate formed in a firstsurface on a second direction side of the first glass substrate; asecond polarizing plate formed in a first surface on a first directionside of the third glass substrate; and an bonding layer disposed betweenthe first polarizing plate and the second polarizing plate. In planarview, the bonding layer overlaps outer peripheral ends of the firstpolarizing plate and the second polarizing plate, a surface on the firstdirection side of the bonding layer bonds to a surface on the seconddirection side of the first polarizing plate, and a surface on thesecond direction side of the bonding layer bonds to a surface on thefirst direction side of the second polarizing plate.

In the liquid crystal display device, a thickness of the bonding layermay be larger than a total of thicknesses of the first polarizing plateand the second polarizing plate.

In the liquid crystal display device, surface roughening may beperformed on at least one of a surface on the second direction side ofthe first polarizing plate and a surface on the first direction side ofthe second polarizing plate.

In the liquid crystal display device, a gap may be formed in a regionbetween the first polarizing plate and the second polarizing plate.

In the liquid crystal display device, the bonding layer may include afirst portion and a second portion having weaker adhesive strength thanthe first portion.

In the liquid crystal display device, an opening may be formed in a partof the bonding layer.

In the liquid crystal display device, the bonding layer may include afirst portion disposed along a side where a driving circuit is disposedand a second portion disposed opposite to the first portion, and theopening may be formed in the first portion and the second portion.

In the liquid crystal display device, each of the display panels mayinclude a chip on film (COF) portion, and the bonding layer may bedisposed in a region where the COF portion is avoided in planar view.

The present disclosure can reduce the cost of the liquid crystal displaydevice in which the plurality of display panels overlap each other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a schematic configuration ofliquid crystal display device of a first exemplary embodiment;

FIG. 2 is a plan view illustrating a schematic configuration of liquidcrystal display device according to the first exemplary embodiment;

FIG. 3 is a plan view illustrating a schematic configuration of displaypanel;

FIG. 4 is a plan view illustrating a schematic configuration of displaypanel;

FIG. 5 is a sectional view taken along line A-A′ in FIGS. 3 and 4;

FIGS. 6A and 6B are plan views illustrating an exemplary pixelconfiguration of display panel 100 and display panel 200 of the firstexemplary embodiment;

FIG. 7 is a view illustrating a stuck portion of display panel 100 anddisplay panel 200 of the first exemplary embodiment;

FIG. 8 illustrates disposition of bonding layer in planar view of liquidcrystal display device;

FIG. 9 is a sectional view illustrating liquid crystal display deviceaccording to the second exemplary embodiment;

FIG. 10 is a view illustrating a stuck portion of display panel 100 anddisplay panel 200 of the second exemplary embodiment;

FIG. 11 illustrates a part of the enlarged stuck portion between displaypanel 100 and display panel 200;

FIG. 12 is a plan view illustrating another schematic configuration ofdisplay panel of each exemplary embodiment;

FIG. 13 is a plan view illustrating another schematic configuration ofdisplay panel of each exemplary embodiment;

FIG. 14 is a plan view illustrating another schematic configuration ofdisplay panel of each exemplary embodiment;

FIG. 15 is a plan view illustrating another schematic configuration ofdisplay panel of each exemplary embodiment;

FIGS. 16A and 16B are plan views illustrating another schematicconfiguration of display panel of each exemplary embodiment; and

FIGS. 17A and 17B are plan views illustrating another schematicconfiguration of display panel of each exemplary embodiment.

DETAILED DESCRIPTION

Hereinafter, an exemplary embodiment of the present disclosure will bedescribed with reference to the drawings. A liquid crystal displaydevice according to the present exemplary embodiment includes aplurality of display panels that display images, a plurality of drivingcircuits (a plurality of source drivers and a plurality of gate drivers)that drive the display panels, a plurality of timing controllers thatcontrol the driving circuits, an image processor that performs imageprocessing on input image data input from an outside and outputs imagedata to each of the timing controllers, and a backlight that irradiatesthe plurality of display panels with light from a rear surface side.There is no limitation to a number of display panels, but it is onlynecessary to provide at least two display panels. When viewed from anobserver side, the plurality of display panels are disposed whileoverlapping each other in a front-back direction. An image is displayedon each of the display panels. Liquid crystal display device 10including two display panels will be described below by way of example.

First Exemplary Embodiment

FIG. 1 is a perspective view illustrating a schematic configuration ofliquid crystal display device 10 of a first exemplary embodiment. Asillustrated in FIG. 1, liquid crystal display device 10 includes displaypanel 100 disposed at a position (front side) closer to an observer,display panel 200 disposed at a position (rear side) farther away fromthe observer with respect to display panel 100, adhesive layer 400 inwhich display panel 100 and display panel 200 adhere to each other,backlight 500 disposed on the rear surface side of display panel 200,and front chassis 600 that covers display panel 100 and display panel200 from the display surface side.

FIG. 2 is a plan view illustrating a schematic configuration of liquidcrystal display device 10 according to the first exemplary embodiment.As illustrated in FIG. 2, display panel 100 includes first source driver120 and first gate driver 130, and display panel 200 includes secondsource driver 220 and second gate driver 230. Liquid crystal displaydevice 10 includes first timing controller 140 that controls firstsource driver 120 and first gate driver 130, second timing controller240 that controls second source driver 220 and second gate driver 230,and image processor 300 that outputs image data to first timingcontroller 140 and second timing controller 240. For example, displaypanel 100 displays a color image in first image display region 110according to the input video signal, and display panel 200 displays ablack-and-white image in second image display region 210 according tothe input video signal. Image processor 300 receives input video signalData transmitted from an external system (not illustrated), performspredetermined image processing on input video signal Data, outputs firstimage data DAT1 to first timing controller 140, and outputs second imagedata DAT2 to second timing controller 240. Image processor 300 alsooutputs control signals CS1, CS2 (see FIGS. 3 and 4) such as asynchronizing signal to first timing controller 140 and second timingcontroller 240. First image data DAT1 is image data for displaying thecolor image, and second image data DAT2 is image data for displaying theblack-and-white image. Display panel 100 may display the black-and-whiteimage while display panel 200 displays the color image, or both displaypanels 100, 200 may display the black-and-white image or the colorimage.

FIG. 3 is a plan view illustrating a schematic configuration of displaypanel 100, and FIG. 4 is a plan view illustrating a schematicconfiguration of display panel 200. FIG. 5 is a sectional view takenalong line A-A′ in FIGS. 3 and 4.

A configuration of display panel 100 will be described with reference toFIGS. 3 and 5. As illustrated in FIG. 5, display panel 100 includes thinfilm transistor substrate 101 disposed on a side (second direction side)of backlight 500, counter substrate 102, which is disposed on theobserver side (first direction side) while being opposite to thin filmtransistor substrate 101, and liquid crystal layer 103 disposed betweenthin film transistor substrate 101 and counter substrate 102. Polarizingplate 104 is disposed on the side of backlight 500 of display panel 100,and polarizing plate 105 is disposed on the observer side.

In thin film transistor substrate 101, as illustrated in FIG. 3, aplurality of source lines 111 extending in a column direction, and aplurality of gate lines 112 extending in a row direction are formed, andthin film transistor 113 is formed near an intersection between each ofthe plurality of source lines 111 and each of the plurality of gatelines 112. In planar view of display panel 100, a region surrounded bytwo source lines 111 adjacent to each other and two gate lines 112adjacent to each other is defined as one pixel 114, and a plurality ofpixels 114 are arranged in a matrix form (the row direction and thecolumn direction). In thin film transistor substrate 101, pixelelectrode 115 is formed in each pixel 114, and one common electrode (notillustrated) common to the plurality of pixels 114 is formed.

Although not illustrated, a plurality of colored portions each of whichcorresponds to pixel 114 are formed on counter substrate 102. Eachcolored portion is surrounded by black matrix blocking lighttransmission. For example, each colored portion is formed into arectangular shape. The plurality of colored portions include redportions made of a red (R color) material to transmit red light, greenportions made of a green (G color) material to transmit green light, andblue portions made of a blue (B color) material to transmit blue light.One of the red portions, one of the green portions, and one of the blueportions are repeatedly arranged in this order in the row direction, thecolored portions having the same color are arranged in the columndirection, and black matrices are formed in boundaries of coloredportions adjacent in the row direction and the column direction.According to colored portions, the plurality of pixels 114 include redpixels 114R corresponding to the red portions, green pixels 114Gcorresponding to the green portions, and blue pixels 114B correspondingto the blue portions as illustrated in FIG. 3. In display panel 100, redpixels 114R, green pixels 114G, and blue pixels 114B are repeatedlyarrayed in the row direction in this order, and pixels 114 having theidentical color are arrayed in the column direction.

Based on first image data DAT1 and first control signal CS1 (such as aclock signal, a vertical synchronizing signal, and a horizontalsynchronizing signal), which are received from image processor 300,first timing controller 140 generates first image data DA1 and firsttiming signals (data start pulse DSP1, data clock DCK1, gate start pulseGSP1, and gate clock GCK1) to control drive of first source driver 120and first gate driver 130 (see FIG. 3). First timing controller 140outputs first image data DA1, data start pulse DSP1, and data clock DCK1to first source driver 120, and outputs gate start pulse GSP1 and gateclock GCK1 to first gate driver 130.

First source driver 120 outputs a data signal (data voltage, gradationvoltage) corresponding to first image data DA1 to source lines 111 basedon data start pulse DSP1 and data clock DCK1. First gate driver 130outputs a gate signal (gate voltage) to gate lines 112 based on gatestart pulse GSP1 and gate clock GCK1. Consequently, in display panel100, a color image is displayed by supply of a desired data voltage tosource lines 111 connected to pixel electrode 115 of each of red pixel114R, green pixel 114G, and blue pixel 114B.

A configuration of display panel 200 will be described below withreference to FIGS. 4 and 5. As illustrated in FIG. 5, display panel 200includes thin film transistor substrate 201 disposed on the side ofbacklight 500, counter substrate 202, which is disposed on the observerside while being opposite to thin film transistor substrate 201, andliquid crystal layer 203 disposed between thin film transistor substrate201 and counter substrate 202. Polarizing plate 204 is disposed on theside of backlight 500 of display panel 200, and polarizing plate 205 isdisposed on the observer side.

In thin film transistor substrate 201, as illustrated in FIG. 4, aplurality of source lines 211 extending in the column direction, and aplurality of gate lines 212 extending in the row direction are formed,and thin film transistor 213 is formed near the intersection betweeneach of the plurality of source lines 211 and each of the plurality ofgate lines 212. In planar view of display panel 200, a region surroundedby two source lines 211 adjacent to each other and two gate lines 212adjacent to each other is defined as one pixel 214, and a plurality ofpixels 214 are arranged in a matrix form (the row direction and thecolumn direction). In thin film transistor substrate 201, pixelelectrode 215 is formed in each pixel 214, and one common electrode (notillustrated) common to the plurality of pixels 214 is formed.

Although not illustrated, in counter substrate 202, the black matrixblocking light transmission is formed at a position corresponding to aboundary of each pixel 214. The colored portion is not formed in aregion surrounded by the black matrix. For example, an overcoat film isformed in the region.

Based on second image data DAT2 and second control signal CS2 (such as aclock signal, a vertical synchronizing signal, and a horizontalsynchronizing signal), which are received from image processor 300,second timing controller 240 generates second image data DA2 and secondtiming signals (data start pulse DSP2, data clock DCK2, gate start pulseGSP2, and gate clock GCK2) to control drive of second source driver 220and second gate driver 230 (see FIG. 4). Second timing controller 240outputs second image data DA2, data start pulse DSP2, and data clockDCK2 to second source driver 220, and outputs gate start pulse GSP2 andgate clock GCK2 to second gate driver 230.

Second source driver 220 outputs the data voltage corresponding tosecond image data DA2 to source lines 211 based on data start pulse DSP2and data clock DCK2. Second gate driver 230 outputs the gate voltage togate lines 212 based on gate start pulse GSP2 and gate clock GCK2.Consequently, the black-and-white image is displayed on display panel200.

Each pixel 114 of display panel 100 and each pixel 214 of display panel200 are disposed on three-to-one correspondence, and overlap each otherin planar view. For example, as illustrated in FIGS. 6A and 6B, threepixels 114 (red pixel 114R, green pixel 114G, and blue pixel 114B) (seeFIG. 6A) of display panel 100 and one pixel 214 (see FIG. 6B) of displaypanel 200 overlap each other in planar view. Each pixel 114 of displaypanel 100 and each pixel 214 of display panel 200 may be disposed inone-to-one correspondence, and one pixel 114 of display panel 100 andone pixel 214 of display panel 200 may overlap each other in planarview.

FIG. 7 is a view illustrating a stuck portion of display panel 100 anddisplay panel 200 of the first exemplary embodiment. Thin filmtransistor substrate 101 of display panel 100 includes glass substrate101 a and TFT element layer 101 b formed on a surface on the observerside of glass substrate 101 a. TFT element layer 101 b includes variouscomponents (such as source line 111, gate line 112, thin film transistor113, pixel electrode 115, and a common electrode). Polarizing plate 104is stuck to a surface on the backlight side of glass substrate 101 awith an adhesive agent interposed therebetween. Counter substrate 202 ofdisplay panel 200 includes glass substrate 202 a and CF element layer202 b formed on a surface on the backlight side of glass substrate 202a. CF element layer 202 b includes various components (such as a colorfilter and the black matrix). Polarizing plate 205 is stuck to a surfaceon the observer side of glass substrate 202 a with an adhesive agentinterposed therebetween.

As illustrated in FIG. 7, display panel 100 and display panel 200 arestuck and fixed by bonding layer 400. For example, a double sided tapeor a silicone resin based bonding agent can be used as bonding layer400. Specifically, bonding layer 400 is disposed at an outer peripheralend between polarizing plate 104 of display panel 100 and polarizingplate 205 of display panel 200. That is, bonding layer 400 overlaps theouter peripheral ends of polarizing plate 104 and polarizing plate 205in planar view. Air gap 410 (gap) is formed in a region surrounded bybonding layer 400. In a process of sticking display panel 100 anddisplay panel 200, one of surfaces of the double sided tape (bondinglayer 400) is stuck to the outer peripheral end of the surface on theobserver side of polarizing plate 205 of display panel 200, and theother surface of the double sided tape is stuck to the outer peripheralend of the surface on the backlight side of polarizing plate 104 whiledisplay panel 100 is overlapped. Consequently, polarizing plates 104,205 are stuck to each other with bonding layer 400 interposedtherebetween, thereby fixing display panel 100 and display panel 200.

FIG. 8 illustrates disposition of bonding layer 400 in planar view ofliquid crystal display device 10. In FIG. 8, for convenience, onlybonding layer 400 is illustrated while other components are eliminated.Bonding layer 400 includes first portion 400 a, second portion 400 b,third portion 400 c, and fourth portion 400 d each of which extends intoa rectangular shape, first portion 400 a is disposed along upper side 10a of liquid crystal display device 10, second portion 400 b is disposedalong left side 10 b of liquid crystal display device 10, third portion400 c is disposed along lower side 10 c of liquid crystal display device10, and fourth portion 400 d is disposed along right side 10 d of liquidcrystal display device 10. First portion 400 a, second portion 400 b,third portion 400 c, and fourth portion 400 d are disposed along anouter periphery of liquid crystal display device 10 while coupled toeach other. Air gap 410 is formed in the region surrounded by bondinglayer 400 (first portion 400 a, second portion 400 b, third portion 400c, and fourth portion 400 d). As illustrated in FIGS. 7 and 8, air gap410 is a closed space. In the case that the double sided tape is used asbonding layer 400, the coupling portion of first portion 400 a, secondportion 400 b, third portion 400 c, and fourth portion 400 d may beseparated in consideration of work efficiency.

In the above configuration, bonding layer 400 is disposed not in aninside region of liquid crystal display device 10 (polarizing plate) butat the outer peripheral end of liquid crystal display device 10, so thatthe cost can be reduced compared with the conventional configuration inwhich the bonding layer is disposed over the whole surface of the liquidcrystal display device (polarizing plate). The closed space (air gap410) is formed between display panel 100 and display panel 200, and airflowing into and out liquid crystal display device 10 is interrupted, sothat mixing of foreign matters can be prevented.

Second Exemplary Embodiment

A second exemplary embodiment of the present disclosure will bedescribed below with reference to the drawings. For convenience, thesame component as that of the first exemplary embodiment is designatedby the same numeral, and the description will be omitted. In the secondexemplary embodiment, the term defined in the first exemplary embodimentis used according to the definition of the first exemplary embodimentunless otherwise noted.

FIG. 9 is a sectional view illustrating liquid crystal display device 10according to the second exemplary embodiment. Liquid crystal displaydevice 10 of the second exemplary embodiment differs from liquid crystaldisplay device 10 (see FIG. 5) of the first exemplary embodiment in theconfigurations of polarizing plates 104, 205 and bonding layer 400 andthe other configuration is the same as that of the first exemplaryembodiment.

FIG. 10 is a view illustrating a stuck portion of display panel 100 anddisplay panel 200 of the second exemplary embodiment. In liquid crystaldisplay device 10 of the second exemplary embodiment, bonding layer 400is the outer peripheral end between glass substrate 101 a of displaypanel 100 and glass substrate 202 a of display panel 200, and isdisposed in a region outside polarizing plates 104, 205. Polarizingplates 104, 205 are disposed in the region surrounded by bonding layer400, and air gap 410 (gap) is formed between polarizing plates 104, 205.Thickness t1 of bonding layer 400 is larger than a total of thicknessesof polarizing plates 104, 205. For example, in the case that the doublesided tape is used as bonding layer 400, thickness t1 of the doublesided tape can be set to 0.6 mm, and the thickness of each of polarizingplates 104, 205 can be set to 0.26 mm. In the process of stickingdisplay panel 100 and display panel 200, one of the surfaces of thedouble sided tape (bonding layer 400) is stuck to the outer peripheralend outside polarizing plate 205 in the surface on the observer side ofglass substrate 202 a of display panel 200, and the other surface of thedouble sided tape is stuck to the outer peripheral end outsidepolarizing plate 104 in the surface on the backlight side of glasssubstrate 101 a while display panel 100 is overlapped. Consequently,glass substrate 101 a, 202 a are stuck to each other with bonding layer400 interposed therebetween, thereby fixing display panel 100 anddisplay panel 200.

In the above configuration, the cost can be reduced similarly to thefirst exemplary embodiment. In the above configuration, a distance (airgap 410) between display panel 100 and display panel 200 can be narrowedcompared with the first exemplary embodiment (see FIG. 7). Thus, aproblem of a display defect (for example, the display image is seendouble) caused by the large distance of air gap 410 can be suppressed.Thickness t1 of bonding layer 400 can be thickened larger than the totalof the thicknesses of polarizing plates 104, 205 compared with the firstexemplary embodiment, and bonding layer 400 can be bonded to a glasssurface having excellent flatness. Consequently, the bonding strength(adhesive strength) can be improved, and sticking force between displaypanel 100 and display panel 200 can be improved.

In the configuration of the second exemplary embodiment, because air gap410 is narrowed, polarizing plates 104, 205 may come into partialcontact with each other due to a warp of display panels 100, 200 orpolarizing plates 104, 205 In the case that polarizing plates 104, 205come into partial contact with each other, light interferes with eachother (Newton ring) at a boundary between a contact portion and anon-contact portion, and the image quality may be degraded.

For this reason, in liquid crystal display device 10 of the secondexemplary embodiment, surfaces of polarizing plates 104, 205 facing eachother, namely, the surface facing polarizing plate 205 in polarizingplate 104 and the surface facing polarizing plate 104 in polarizingplate 205 are subjected to surface roughening (anti-glare treatment) toform minute irregularities as illustrated in FIG. 11. FIG. 11illustrates a part of the enlarged stuck portion between display panel100 and display panel 200. Polarizing plate 104 includestriacetylcellulose (TAC) layers 104 a, 104 c of a substrate film andpolarizing layer 104 b (PVA layer) of a polarizing film (polarizer)disposed between TAC layers 104 a, 104 c. Similarly, polarizing plate205 includes TAC layers 205 a, 205 c of a substrate film and polarizinglayer 205 b (PVA layer) of a polarizing film (polarizer) disposedbetween TAC layers 205 a, 205 c. Although not illustrated, each ofpolarizing plates 104, 205 includes a protective film and an adhesive(release film).

As illustrated in FIG. 11, the surface facing TAC layer 205 c in TAClayer 104 c and the surface facing TAC layer 104 c in TAC layer 205 care subjected to the surface roughening to form the minuteirregularities. A known method such as sand blasting and embossing canbe adopted to the surface roughening. Alternatively, a binder resinlayer containing fine particles may be formed. At this point, preferablyrefractive indices of the fine particle and the binder are substantiallyequalized to each other in order to decrease diffusion of light. In theabove configuration, even if air gap 410 is narrowed, the contactportions of the surfaces facing each other in polarizing plates 104, 205are dispersed, so that the light interference can be suppressed. Thesurface roughening may be performed on both the surface of polarizingplate 104 and the surface of polarizing plate 205 or only one of thesurface of polarizing plate 104 and the surface of polarizing plate 205.

Liquid crystal display device 10 of the present disclosure is notlimited to the above configurations. For example, as illustrated in FIG.12, a part (in this case, first portion 400 a) of bonding layer 400 maybe weaker than other portions (second portion 400 b, third portion 400c, and fourth portion 400 d) in the adhesive strength. For example, inthe case that the double sided tape is used as bonding layer 400, afterone of the surfaces of each of first portion 400 a, second portion 400b, third portion 400 c, and fourth portion 400 d is stuck to glasssubstrate 202 a of display panel 200, a release paper on the othersurface is peeled off only in first portion 400 a, and release papers onthe other surface of each of second portion 400 b, third portion 400 c,and fourth portion 400 d are left. Then, the other surface of firstportion 400 a is stuck to one side (a side corresponding to upper side10 a of liquid crystal display device 10) of glass substrate 101 a whiledisplay panel 100 is overlapped. At this point, display panel 100 anddisplay panel 200 are stuck only at one side, so that display panels100, 200 can be aligned with each other. After display panel 100 anddisplay panel 200 are aligned with each other, the release papers ofsecond portion 400 b, third portion 400 c, and fourth portion 400 d arepeeled off, and second portion 400 b, third portion 400 c, and fourthportion 400 d are stuck to the remaining three sides of glass substrate101 a. Consequently, display panel 100 and display panel 200 are stuckand fixed by bonding layer 400. In the above configuration, displaypanel 100 and display panel 200 can accurately be aligned with eachother. Because a part of bonding layer 400 has the weak adhesivestrength, display panel 100 and display panel 200 are easily peeled off,and workability can be improved during repair.

There is no limitation on a place and the number of the portions wherebonding layer 400 has the weak adhesive strength. For example, asillustrated in FIG. 13, fifth portion 400 e having weaker adhesivestrength than first portion 400 a, second portion 400 b, third portion400 c, and fourth portion 400 d may be disposed at positionscorresponding to four corners of liquid crystal display device 10.

For example, as illustrated in FIG. 14, a part (in this case, firstportion 400 a) of bonding layer 400 may be eliminated as anotherconfiguration of liquid crystal display device 10. That is, opening 400f may be formed in a part of bonding layer 400. In this configuration,the region (air gap 410) between display panel 100 and display panel 200is not closed, but the air can flow in and out, so that peel-off of thebonding between display panel 100 and display panel 200 due to thermalexpansion of the air in the region can be prevented.

In the configuration of FIG. 14, opening 400 f may further be formed ina portion on the side where a driving circuit (such as the source driverand the gate driver) is disposed in bonding layer 400 and an oppositeportion to the portion. In an example of FIG. 15, openings 400 f areformed in third portion 400 c on the side (lower side 10 c) where thesource driver is disposed and first portion 400 a on the opposite side(upper side 10 a). In the above configuration, an air flow is generatedin the region (air gap 410) between display panel 100 and display panel200, so that a heat radiation effect for liquid crystal display device10 can be obtained. In the above configuration, opening 400 f may beprovided in at least one point of each two sides facing each other, butthere is no limitation on the number of openings 400 f.

As to another configuration of liquid crystal display device 10, forexample, as illustrated in FIGS. 16A and 16B, bonding layer 400 may bedisposed in a region where a chip on film (COF) portion of display panel200 is avoided (FIG. 16B), and stuck to display panel 100 (FIG. 16A). Inthe configuration of FIGS. 16A and 16B, the double sided tape may beused as bonding layer 400. However, preferably a silicone resin basedbonding agent is used in consideration of workability. As illustrated inFIGS. 17A and 17B, bonding layer 400 may be disposed in a wholeperiphery of display panel 200 so as to cover an upper portion of theCOF portion of display panel 200 (FIG. 17B), and stuck to display panel100 (FIG. 17A). In the configuration of FIGS. 16A and 16B, the doublesided tape may be used as bonding layer 400. However, preferably thesilicone resin based bonding agent is used in consideration of a step ofthe COF portion and the like.

While there have been described what are at present considered to becertain embodiments of the application, it will be understood thatvarious modifications may be made thereto, and it is intended that theappended claims cover all such modifications as fall within the truespirit and scope of the invention.

What is claimed is:
 1. A liquid crystal display device in which aplurality of display panels are disposed while overlapping each other,and an image being displayed on each of the display panels, the liquidcrystal display device comprising: a first glass substrate; a secondglass substrate disposed opposite to a first direction with respect tothe first glass substrate; a first liquid crystal layer disposed betweenthe first glass substrate and the second glass substrate; a third glasssubstrate disposed opposite to the first glass substrate in a seconddirection, the second direction being an opposite direction to the firstdirection with respect to the first glass substrate; a fourth glasssubstrate disposed opposite to the second direction with respect to thethird glass substrate; a second liquid crystal layer disposed betweenthe third glass substrate and the fourth glass substrate; a firstpolarizing plate formed in a first surface on a second direction side ofthe first glass substrate; a second polarizing plate formed in a firstsurface on a first direction side of the third glass substrate; and abonding layer disposed between the first glass substrate and the thirdglass substrate, wherein in planar view, the bonding layer is disposedoutside the first polarizing plate and the second polarizing plate, asurface on the first direction side of the bonding layer bonds to thefirst surface of the first glass substrate, and a surface on the seconddirection side of the bonding layer bonds to the first surface of thethird glass substrate.
 2. The liquid crystal display device according toclaim 1, wherein a thickness of the bonding layer is larger than a totalof thicknesses of the first polarizing plate and the second polarizingplate.
 3. The liquid crystal display device according to claim 1,wherein surface roughening is performed on at least one of a surface onthe second direction side of the first polarizing plate and a surface onthe first direction side of the second polarizing plate.
 4. The liquidcrystal display device according to claim 1, wherein a gap is formed ina region between the first polarizing plate and the second polarizingplate.
 5. The liquid crystal display device according to claim 1,wherein the bonding layer includes a first portion and a second portionhaving weaker adhesive strength than the first portion.
 6. The liquidcrystal display device according to claim 1, wherein an opening isformed in a part of the bonding layer.
 7. The liquid crystal displaydevice according to claim 6, wherein the bonding layer includes a firstportion disposed along a side where a driving circuit is disposed and asecond portion disposed opposite to the first portion, and the openingis formed in the first portion and the second portion.
 8. The liquidcrystal display device according to claim 1, wherein each of the displaypanels includes a chip on film (COF) portion, and the bonding layer isdisposed in a region where the COF portion is avoided in planar view. 9.A liquid crystal display device in which a plurality of display panelsare disposed while overlapping each other, and an image being displayedon each of the display panels, the liquid crystal display devicecomprising: a first glass substrate; a second glass substrate disposedopposite to a first direction with respect to the first glass substrate;a first liquid crystal layer disposed between the first glass substrateand the second glass substrate; a third glass substrate disposedopposite to the first glass substrate in a second direction, the seconddirection being an opposite direction to the first direction withrespect to the first glass substrate; a fourth glass substrate disposedopposite to the second direction with respect to the third glasssubstrate; a second liquid crystal layer disposed between the thirdglass substrate and the fourth glass substrate; a first polarizing plateformed in a first surface on a second direction side of the first glasssubstrate; a second polarizing plate formed in a first surface on afirst direction side of the third glass substrate; and a bonding layerdisposed between the first polarizing plate and the second polarizingplate, wherein in planar view, the bonding layer overlaps outerperipheral ends of the first polarizing plate and the second polarizingplate, a surface on the first direction side of the bonding layer bondsto a surface on the second direction side of the first polarizing plate,and a surface on the second direction side of the bonding layer bonds toa surface on the first direction side of the second polarizing plate.10. The liquid crystal display device according to claim 9, wherein agap is formed in a region between the first polarizing plate and thesecond polarizing plate.
 11. The liquid crystal display device accordingto claim 9, wherein the bonding layer includes a first portion and asecond portion having weaker adhesive strength than the first portion.12. The liquid crystal display device according to claim 9, wherein anopening is formed in a part of the bonding layer.
 13. The liquid crystaldisplay device according to claim 12, wherein the bonding layer includesa first portion disposed along a side where a driving circuit isdisposed and a second portion disposed opposite to the first portion,and the opening is formed in the first portion and the second portion.14. The liquid crystal display device according to claim 9, wherein eachof the display panels includes a chip on film (COF) portion, and thebonding layer is disposed in a region where the COF portion is avoidedin planar view.